1. Field of the Invention
The invention relates to a semiconductor device and a manufacturing method thereof, particularly to a package type semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
CSP (Chip Size Package) has been pursued as a package type semiconductor device. The CSP means a small package having almost the same outside dimensions as those of a semiconductor die packaged in it.
Conventionally, a BGA (Ball Grid Array) type semiconductor device has been known as a kind of CSP. In this BGA type semiconductor device, a plurality of ball-shaped conductive terminals made of a metal such as solder is arrayed in a grid pattern on one surface of the package, and electrically connected with the semiconductor die mounted on the other side of the package.
When this BGA type semiconductor device is mounted on electronic equipment, the semiconductor die is electrically connected with an external circuit on a printed circuit board by compression bonding of the conductive terminals to wiring patterns on the printed circuit board.
The conventional BGA type semiconductor device will be described as an example of the conventional package type semiconductor device next, with reference to drawings. FIGS. 26A and 26B show an outline structure of the conventional BGA type semiconductor device. FIG. 26A is an oblique perspective figure showing a top side of the BGA type semiconductor device. FIG. 26B is an oblique perspective figure showing a bottom side of the BGA type semiconductor device.
A semiconductor die 104 is sealed between a first glass substrate 102 and a second glass substrate 103 through epoxy resin layers 105a and 105b in the BGA type semiconductor device 101. Electronic devices (not shown) are formed on a top surface of the semiconductor die 104. A plurality of conductive terminals 106 is arrayed in a grid pattern on a surface of the second glass substrate 103, that is, on the bottom surface of the BGA type semiconductor device 101. The conductive terminals 106 are connected to the semiconductor die 104 through a plurality of second wirings 110. The plurality of second wirings 110 is connected with first wirings pulled out from inside of the semiconductor die 104, making each of the conductive terminals 106 electrically connected with the semiconductor die 104.
More detailed explanation on a cross-sectional structure of the BGA type semiconductor device 101 will be given hereafter referring to FIG. 27. FIG. 27 shows a cross-sectional view of the BGA type semiconductor devices 101 separated into individual dice along dicing lines.
A first wiring 107 is provided on an insulation film 108 on the top surface of the semiconductor die 104. The semiconductor die 104 is bonded to the first glass substrate 102 with the resin layer 105a. A bottom surface of the semiconductor die 104 is bonded to the second glass substrate 103 with the resin layer 105b. 
One end of the first wiring 107 is connected to the second wiring 110. The second wiring 110 extends from the end of the first wiring 107 onto a surface of the second glass substrate 103. The ball-shaped conductive terminal 106 is formed on the second wiring 110 extended onto the second glass substrate 103.
The technology mentioned above is disclosed, for example, in Japanese Patent Application Publication No. 2002-512436.
However, there is a problem of making steps complex in a manufacturing process of the conventional package type semiconductor device 101. This causes a problem of increasing a manufacturing cost.
Furthermore, the reliability of the described semiconductor device 101 is not enough because of having a complex structure. For example, there is a possibility that the first wiring 107 and the second wiring 110 are disconnected at a point of contact between them, since the area of the point of contact is very small in the BGA type semiconductor device 101 described above. Also there is a problem in step coverage of the second wiring 110.
Furthermore, the semiconductor device 101 is mounted on the circuit board by connecting the ball-shaped conductive terminals 106 formed on its bottom side to the circuit board, the conductive terminals 106 facing the circuit board. Therefore, there is a problem of slanting or missetting of the semiconductor device 101. When the electronic device (not shown) is a light receiving element such as a CCD (Charge Coupled Device), the slanting or missetting causes a blur in an image taken.
As a package type semiconductor device which can prevent the manufacturing cost increase, there has been known a semiconductor device in which a semiconductor die and a circuit board are connected through bonding wire. However, such a semiconductor device can not be formed with a protection layer on its top surface, so that the top surface is exposed. This protection layer is to be provided for protecting the top surface of the semiconductor device from mechanical damage or moisture. When dust is attached to the top surface of the protection layer, the protection layer can be cleaned. Therefore, in the semiconductor device without the protection layer, there is a problem that reliability of the electronic device (not shown) and so on formed on the top surface lowers.